According to the World Health Organization (WHO), periodontal disease affects millions of patients worldwide, affecting up to 1 billion adults worldwide. Periodontitis (PD) is characterized by chronic inflammation of the supporting tissues surrounding the teeth, caused by a complex interaction between the host and parasites, which gradually compromises the integrity of the periodontium. It is characterized by a bacterial-induced inflammatory response and destruction of periodontal tissues, including the periodontal ligament, cementum, and alveolar bone.
The more severe stages of periodontitis (stages III and IV) affect more than 700 million people, approximately 11% of the global population. In fact, Parkinson’s disease is the sixth most common chronic disease worldwide and is considered the leading cause of tooth loss in adults. Therefore, Parkinson’s disease poses a major public health challenge due to its high prevalence and the heavy burden of tooth loss and impaired chewing function, which negatively affects quality of life.
Importantly, a history of PD is a significant risk factor for peri-implantitis, an irreversible pathological condition that occurs in the tissues surrounding dental implants. Historically, there has been a lack of consensus on the true prevalence of peri-implantitis, with heterogeneity in results attributed to differences in disease definitions and the lack of a standard diagnosis. However, contrary to previous assumptions, peri-implantitis as a biological complication has been severely underestimated for many years.
It was not until the 2017 World Symposium on the Classification of Periodontal and Peri-implant Diseases and Conditions that clinical parameters became better defined, revealing a much higher prevalence of the disease than expected. As a result, recent studies report alarming rates of peri-implantitis, ranging from 34% to 56% of patients within a mean of 2 to 7.8 years after prosthetic placement.
These figures underscore not only the public’s concerns about peri-implantitis, but also the heavy economic burden it imposes. In light of this, the global peri-implantitis treatment market is expected to reach a value of $4.5 billion by 2032. Obviously, these projections are based on the increasing number of dental implants that have been and will be used for oral restorations. The alarming prevalence of peri-implantitis further suggests that current clinical procedures aimed at preventing and treating peri-implantitis are inadequate.
The main pathogenic factor of peri-implantitis is the biofilm accumulated on the implant components at the tissue-oral interface. Therefore, non-surgical supportive therapy to remove the biofilm is a necessary step in the initial stage of peri-implantitis treatment.
The treatment of peri-implantitis ranges from non-surgical to surgical, depending on the results of the initial steps. Regardless of the method chosen, the main goal of treatment is to completely eliminate the inflammation by removing the biofilm and eliminating microbial agents. In view of this, several methods have been described to achieve surface decontamination, such as the use of antiseptics, topical and systemic antibiotic treatment, and laser and antimicrobial photodynamic therapy. However, the limited number of studies supporting the benefits of adjunctive treatments compromises the reliability of the evidence and makes the evaluation of conventional treatments difficult.
Biomaterials offer a range of possibilities for the development of therapeutic interventions, from the use of polymer films with antimicrobial effects on dental implant surfaces to the use of drug delivery systems and even titanium modification on implant/abutment surfaces to prevent and/or treat peri-implantitis.
However, despite the large number of antimicrobial coating approaches discussed in the literature, to date, none of the proposed surfaces has reached the commercial stage. A well-designed review It is clear that the number of articles published in the field of antimicrobial coatings is increasing, with preclinical studies being a possible highlight. This result confirms that the stagnation in clinical applications may be attributed to the complexity of the factors involved in the development of antimicrobial coatings, from product construction to product application.
In fact, the problem of translating preclinical research results into clinical applications is partly attributed to cytotoxicity, material behavior, drug release control, and the duration of the product’s antimicrobial activity to make it clinically feasible. However, the lack of knowledge about the clinical usefulness of the desired material may directly affect the success of antimicrobial coatings.
In fact, understanding the principles behind the development of surface modifications is the first step to successfully obtain new materials. However, when guiding the complexity of biomaterials, the distinction between prevention and treatment must be considered. Since peri-implantitis is an inflammation caused by a dysregulated biofilm attached to the substrate, the prevention strategy is related to the development of materials with direct antimicrobial effects, either through contact killing or antifouling surfaces.
In this context, the material should be able to resist the pH differences caused by food intake and withstand the mechanical action of brushing to maintain its functionality over a long period of time. From a therapeutic perspective, biomaterial-based coatings should be easily degradable, directly combat infection and/or inflammatory responses, and restore the health of peri-implant tissues in patients diagnosed with peri-implantitis by releasing antimicrobial agents and/or substances associated with inhibiting osteoclastogenesis.
To this end, drug delivery technologies are able to deliver therapeutic drugs to the targeted site, minimize off-target accumulation, and improve patient compliance.
Drug release technologies can provide higher local drug concentrations to specific sites on and around implants, thereby immediately acting on implant-associated infections. The basic concept of drug release systems is to create a responsive structure on the surface, called a smart coating, capable of loading the drug and releasing it in a controlled manner over time.
To this end, chemical cross-linking processes and layer-by-layer (LbL) systems made with natural or synthetic polymers may serve as smart strategies to release loaded drugs. Among the technologies for building smart coatings, we will focus on LbL assembly, an attractive strategy to immediately combat installed diseases.
LbL assembly has many advantages, such as high reproducibility of film formation, simple, versatile, flexible and inexpensive process, nano-control of film thickness, and the ability to use a wide range of natural and/or synthetic polymer materials as multivalent species to construct films.
Basically, the LbL approach involves the alternating adsorption of complementary multivalent species on a substrate through electrostatic interactions, hydrogen bonding or other secondary interactions, which will serve as structures for drug incorporation.
Although the research on LbL technology has been expanding in recent years, the challenges of translating it into commercial products may stem from the lack of understanding of the system limitations, the purpose of the coating, and the significance of the disease stage for its application. To our knowledge, this is the first study to break the barriers of characterization of LbL systems, providing detailed chemical and biological information to clarify their rigorous application in terms of physical location and purpose as an antimicrobial coating.
Likewise, we provide a more in-depth overview of the concepts of disease onset and progression to clarify the indications of LbL systems as implant abutment coatings aimed at treating peri-implantitis. Finally, we relate the chemical properties of LbL systems to their functions and discuss the oral cavity as an uncontrolled environment limiting its clinical applicability.
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